U.S. patent number 4,565,191 [Application Number 06/570,458] was granted by the patent office on 1986-01-21 for apparatus and method for performing cuneiform osteotomy.
Invention is credited to D. Barclay Slocum.
United States Patent |
4,565,191 |
Slocum |
January 21, 1986 |
Apparatus and method for performing cuneiform osteotomy
Abstract
An apparatus and method for performing a cuneiform osteotomy as
provided, the apparatus including a drill jig and an osteotomy
guide. The jig has first and second faces which terminate in edges
and which define a recess extending therethrough and intersecting
an edge thereof, the jig further defining a pair of jig bores
extending therethrough in a direction substantially perpendicular
to the first jig face, one of each of the jig bores being disposed
to each side of the recess. The jig bores are each adapted to
properly position a drill bit extending therethrough and into the
bone against which the second jig face is adapted to be disposed
and to which the osteotomy is being performed. The osteotomy guide
has first and second substantially parallel faces which complement
the first jig face and which terminate in lateral edges. The guide
defines a pair of guide bores extending therethrough in a direction
substantially perpendicular to the guide faces, the guide bores
being spaced from each other a distance equal to the spacing of the
jig bores. Therefore, each of the guide bores is adapted to receive
one of the drill bits to permit relative alignment of the jig and
guide with respect to each other and the bone. The guide further
defines a slot extending therethrough across less than the entire
width of the guide and intersecting an edge thereof. The slot
extends at an oblique angle with respect to a line drawn between
the jig bores. Thus, the guide may be mounted to the jig with
either of the guide faces disposed against the first jig face
permitting the guide slot to be disposed in a first and then in a
second angular position with respect to the bone. This facilitates
cutting the bone in first and second cuts to excise a bone wedge of
an angle alpha which is equal to the difference between the first
and second angular positions of the slot.
Inventors: |
Slocum; D. Barclay (Eugene,
OR) |
Family
ID: |
24279726 |
Appl.
No.: |
06/570,458 |
Filed: |
January 12, 1984 |
Current U.S.
Class: |
606/87 |
Current CPC
Class: |
A61B
17/152 (20130101); A61B 17/15 (20130101) |
Current International
Class: |
A61B
17/15 (20060101); A61B 17/14 (20060101); A61F
005/04 () |
Field of
Search: |
;128/92H,92EB,92D,92E,33R,92A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Mancene; Gene
Assistant Examiner: Shedd; C. W.
Attorney, Agent or Firm: Kolisch, Hartwell &
Dickinson
Claims
It is claimed and desired to secure by Letters Patent:
1. An apparatus for performing cuneiform osteotomy comprising:
a jig having first and second faces which terminate in edges and
which define a recess extending therethrough and intersecting an
edge thereof, said jig further defining a pair of jig bores
extending therethrough in a direction substantially perpendicular
to said first jig face, one of each of said jig bores being
disposed to each side of said recess, said jig bores each being
adapted to properly position a drill bit extending therethrough and
into the bone against which said second jig face is to be disposed
and to which the osteotomy is being performed; and
an osteotomy guide having first and second substantially parallel
faces which complement said first jig face and which terminate in
edges, said guide defining a pair of guide bores extending
therethrough in a direction substantially perpendicular to said
guide faces, said guide bores being spaced from each other a
distance equal to the spacing of said jig bores so that each of
said guide bores is adapted to receive one of the drill bits to
permit relative alignment of said jig and said guide with respect
to each other and to the bone, said guide further defining a slot
extending therethrough across less than the entire width of said
guide and intersecting an edge thereof, said slot extending at an
oblique angle with respect to a line drawn between said guide
bores, whereby said guide may be mounted to said jig with either of
said guide faces disposed against said first jig face permitting
said guide slot to be disposed in a first and then a second angular
position with respect to the bone to facilitate cutting the bone in
first and second cuts to cut a bone wedge of an angle alpha which
is equal to the difference between said first and second angular
positions of said slot.
2. The apparatus of claim 1, wherein said jig recess is V-shaped,
having edges which conform to said first and second angular
positions of said slot, whereby said jig provides guidance for a
cutting implement to effect the cutting.
3. The apparatus of claim 1, wherein said jig further defines a
plurality of other jig bores extending through said jig in a
direction substantially perpendicular to said first jig face, at
least one of said other jig bores being disposed on each side of
said recess such that said bores are aligned along a pair of lines
which intersect at the alpha angle, whereby said bores may be used
to drill holes into the bone so that when the bone wedge is removed
leaving a pair of bone faces, displacement of the bone to cause the
bone faces to abut also causes the drilled holes to align, thereby
facilitating the mounting of an osteopathic compression plate.
4. An apparatus for use in performing a cranial tibial cuneiform
osteotomy on a dog, comprising:
a jig having first and second faces which terminate in lateral and
end edges and which define a recess extending therethrough and
intersecting a lateral edge thereof, said jig further defining a
pair of jig bores extending therethrough in a direction
substantially perpendicular to said first jig face, one of each of
said jig bores being disposed to each side of said recess, said jig
bores each being adapted to facilitate removable positioning of a
pin extending therethrough and into the tibia;
an osteotomy guide having first and second substantially parallel
faces which complement said first jig face and which terminate in
lateral and end edges, said guide defining a pair of guide bores
extending therethrough in a direction substantially perpendicular
to said guide faces, said guide bores being spaced from each other
a distance equal to the spacing of said jig bores so that each of
said guide bores is adapted to receive one of the pins to permit
relative alignment of said jig and said guide with respect to each
other and to the bone, said guide further defining a slot extending
therethrough across less than the entire width of said guide and
intersecting a lateral edge thereof, said slot having an open and a
closed end and extending at an oblique angle with respect to a line
drawn between said guide bores, whereby said guide may be mounted
to said jig with either of said guide faces disposed against said
first jig face, permitting said guide slot to be disposed in a
first and then a second angular position with respect to the tibia
to facilitate cutting the tibia in first and second cuts to excise
a bone wedge of an angle alpha which is equal to the difference
between said first and second angular positions of said slot.
5. The apparatus of claim 4, wherein said jig further defines a
plurality of other jig bores extending through said jig in a
direction substantially perpendicular to said first jig face, at
least one of said other jig bores being disposed on each side of
said recess such that said bores are aligned along a pair of lines
which intersect at the alpha angle, whereby said bores maybe used
to drill holes into the tibia so that when the bone wedge is
removed leaving a pair of bone faces, displacement of the tibia to
cause the bone faces to abut also causes the drilled holes to
align, thereby facilitating the mounting of a osteopathic
compression plate.
6. The apparatus of claim 4, wherein said jig recess is V-shaped,
having edges which conform to said first and second angular
positions of said slot, whereby said jig provides guidance for a
cutting implement to effect the cutting.
7. The apparatus of claim 6, wherein a line bisecting said V-shaped
recess bisects the angle formed by said pair of intersecting
lines.
8. The apparatus of claim 6, wherein said notch subtends an angle
of approximately 22.5.degree..
9. The apparatus of claim 4, wherein said jig faces are
substantially planar and parallel and said guide faces are
substantially planar and parallel.
10. The apparatus of claim 9, wherein said jig and said guide
define a continuous hole extending therethrough adjacent said
recess and adjacent said closed end of said slot.
11. A method of performing a cranial tibial cuneiform osteotomy,
comprising:
placing, on an exposed medial side of the tibia, a drill alignment
jig having first and second faces which terminate in lateral and
end edges and which define a recess extending therethrough and
intersecting a lateral edge thereof, the jig further defining at
least two pairs of jig alignment bores extending through the jig in
a direction substantially perpendicular to the first jig face, the
two pairs being disposed on opposite sides of the recess toward
said end edges such that each pair of jig bores is aligned along a
different line, the two lines intersecting at an angle alpha, said
placing causing the second jig face to be positioned against the
tibia with one end edge being disposed proximally and the other
distally;
drilling a proximal hole in the tibia with a drill bit passing
through one of the proximally-disposed jig bores, and leaving the
drill bit in place;
drilling a distal hole in the tibia with a drill bit passing
through one of the distally-disposed jig bores, and leaving the
drill bit in place;
drilling additional holes in the tibia with a drill bit passing
through the jig's remaining bores;
placing, over the jig, an osteotomy guide having first and second
substantially parallel faces which complement the first jig face
and which terminate in lateral and end edges, the guide defining a
pair of guide bores extending therethrough in a direction
substantially perpendicular to the guide faces, the guide bores
being spaced from each other a distance equal to the spacing of the
jig bores, the guide further defining a slot extending therethrough
across less than the entire width of the guide and intersecting a
lateral edge thereof, the slot extending at an oblique angle with
respect to a line drawn between the guide bores, said placing
causing the previously-placed drill bits to extend through the
guide bores and causing the first guide face to be positioned
against the first jig face;
making a first osteotomy cut in the tibia with an osteotomy saw
extending through the guide slot;
turning the guide end over end and placing the second guide face
against the first jig face, with the guide bores receiving the
previously-placed drill bits;
making a second osteotomy cut in the tibia with an osteotomy saw
extending through the guide slot;
removing the guide, jig and drill bits;
removing the bone portion excised by the cuts; and
drawing together and securing the separated portions of the tibia
with interfragmentary compression.
12. The method of claim 11, wherein the first and second osteotomy
cuts are made at an angle of approximately 22.5.degree. with
respect to each other.
13. The method of claim 11, wherein said interfragmentary
compression is applied by placing a compression plate adjacent the
first and second osteotomy cuts, and securing the compression plate
to the tibia with screws extending into the holes drilled in the
tibia.
Description
BACKGROUND OF THE INVENTION
The invention relates generally to osteotomy techniques and more
particularly to an apparatus and method for performing cuneiform
osteotomy.
Various techniques have been developed over the years for
performing cuneiform osteotomy; that is, surgical removal of a bone
wedge such as from a leg bone to correct impairments to the bone,
the musculature or the ligamental support associated therewith.
The cranial or anterior cruciate ligament restrains cranial drawer
or sliding motion of the tibia of a dog. When the cranial cruciate
ligament is disrupted or injured, the tibia moves interiorly with
respect to the femur, leading to further injury of the musculature,
ligaments or meniscus. A wide variety of methods of repairing the
cranial cruciate ligament have been suggested ranging from collagen
ligament implants to synthetic ligament implants. Extra-articular
repair devices have also been proposed, but none of these has been
successful. Collagen implants stretch with use, leaving the knee
area unstable, while synthetic implants are unable to withstand the
varied forces exerted on the knee. Extra-articular repairs decrease
mobility and place undue stress on the soft tissue surrounding the
joint which is not designed for constant loads.
It has been recognized that one problem with most techniques for
repairing a dog's cranial cruciate ligament is that the phenomenon
of cranial tibial thrust has not been appreciated. This phenomenon
results from the natural slope of the tibial plateau which results
in force factors having compressive and cranial or anterior
components. The compressive components are satisfactorily absorbed
by the tibia, as are the cranial tibial forces when the cranial
cruciate ligament is operating satisfactorily. When the cranial
cruciate ligament is weakened by injury or is congenitally
malformed, cranial tibial thrust can be a problem. Many prior
efforts at repair of a weakened cranial cruciate ligament ignore
the cranial tibial thrust phenomenon and have failed to recognize
that this phenomenon results in the ligament being placed under
stress while healing was intended to occur. Such stress clearly
retards or prevents any such healing.
Once cranial cruciate rupture occurs, so-called cranial drawer or
sliding motion, that is, unrestrained motion of the tibia following
such rupture, results in more severe injury to the dog's leg.
Surgical attempts have been addressed to restraining cranial draw
motion but, until recently, no attempt has been made to deal with
internally generated cranial tibial thrust.
The cranial tibial cuneiform osteotomy was developed to address the
cranial tibial thrust phenomenon. It involves removing a wedge from
the distal third of the tibia, and rejoining the bone using an
osteopathic compression plate. This technique flattens the tibial
plane and thereby eliminates cranial tibial thrust, permitting the
cranial cruciate ligament to heal normally in a non-stressed
condition.
While the cranial tibial cuneiform osteotomy has provided a
solution to the afore-described problems, the operation itself has,
until now, been somewhat cumbersome. It has required a substantial
amount of skill in order to remove an appropriate wedge of bone
which would flatten the tibial plane. The positioning of the drill
holes by which the osteopathic compression plate has been mounted
is also critical and has presented another technical problem with
the operation. The operation has been further complicated by the
fact that means has not been provided for supporting the
osteopathic saw during the cutting of the bone. Even for the most
skilled surgeon, this lack of support can and often does present
difficulties. This is an operation which is performed regularly but
typically not on a daily basis so that any device developed to
faciliate the operation should be low in cost, relatively small due
to storage space limitations, and should be easy to use by an
veterinary surgeon who may not perform the operation on a regular
basis.
It is an object of the present invention to provide an apparatus
and method which meets the afore-described problems. More
specifically, the invention has as its objects the following:
(1) to provide a surgical technique which eliminates cranial tibial
thrust forces and thereby causes forces on the tibia to be
compressive rather than angular, facilitating proper healing of the
associated muscles and ligaments;
(2) to provide a device which fac:litates cranial tibial cuneiform
osteotomy by a veterinary surgeon who does not have an opportunity
to perform such operations on a regular basis;
(3) the provision of a device useable in cuneiform osteotomies
which is simple in structure, inexpensive, physically small, and
which will be long-lasting;
(4) to develop an apparatus for performing a cuneiform osteotomy
which facilitates the precise positioning of osteopathic
compression plate holes and which predetermines the exact amount
and shape of bone to be removed; and
(5) to provide an apparatus and method for performing a cuneiform
osteotomy in which the osteopathic saw is supported and precisely
positioned without the use of intricate, expensive equipment, or a
high degree of skill on the part of the surgeon.
SUMMARY OF THE INVENTION
The above objects are best achieved by providing an apparatus for
performing cuneiform osteotomy which includes a jig and an
osteotomy guide. The jig hs first and second faces which terminate
in edges and which define a recess extending therethrough and
intersecting an edge thereof. The jig further defines a pair of jig
bores extending therethrough in a direction substantially
perpendicular to the first jig face, one of each of the jig bores
being dispsoed to each side of the recess, the jig bores each being
adapted to properly position a drill bit extending therethrough and
into the bone against which the second jig face is adapted to be
dispsoed and to which the osteotomy is being performed.
The osteotomy guide has first and second substantially parallel
faces which complement the first jig face and which terminate in
lateral edges. The guide defines as pair of guide bores extending
therethrough in a direction substantially perpendicular to the
guide faces, the guide bores being spaced from each other a
distance equal to the spacing of the jig bores. Therefore, each of
the guide bores is adapted to reeive one of the drill bits to
permit relative alignment of the jig and the guide with respect to
each other and the bone. The guide further defines a slot extending
therethrough across less than the entire width of the guide and
intersecting an edge thereof. The slot extends at an oblique angle
with respect to a line drawn between the guide bores. Thus, the
guide may be mounted to the jig with either of the guide fces
disposed against the first jig face, permitting the guide slot to
be disposed in a first and then in a second angular position with
respect to the bone. This facilitates cutting the bone in first and
second cuts to excise a bone wedge of an angle alpha which is equal
to the difference between the first and second angular positions of
the slot.
Another aspect of the invention is a method of performing a cranial
tibial cuneiform osteotomy using the aforedescribed apparatus.
Specifically, the method comprises the steps of (1) placing the jig
on the exposed medial side of the tibia, (2) drilling aproximal
hole in the tibia with a drill passing through one of the
proximally-disposed jig bores, and leaving the drill bit in place,
(3) drilling a distal hole in the tibia with a drill bit passing
through one of the distally-disposed jig bores, and leaving the
drill bit in place, (4) drilling additional holes in the tibia with
a drill bit passing through the jig's remaining bores, then
removing that drill bit, (5) placing, over the jig, the osteotomy
guide so that the previously-placed drill bits extend through the
guide bores and position the first guide face against the first jig
face, (6) making a first osteotomy cut in the tibia with an
osteotomy saw extending through the guide slot, (7) turning the
guide end over end and placing the second guide face against the
first jig face, with the guide bores receiving the
previously-placed drill bits, (8) making a second osteotomy cut in
the tibia with an osteotomy saw extending through the guide slot,
(9) removing the guide, jig and drill bits, (10) removing the bone
portion excised by the cuts, and (11) drawing together and securing
the separted portions of the tibia with interfragmentary
compression. The interfragmentary compression is normally applied
by placing a compression plate adjacent the first and second
osteotomy cuts, and securing the compression plate to the tibia
with screws extending into the holes previously drilled in the
tibia.
These and other advantages and features of the present invention
will become apparent when consideration is given to the following
detailed description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a first embodiment of drill jig used as a
part of the invention, with an embodiment of an osteotomy guide
depicted in phantom in a first angular position above the drill
jig;
FIG. 2. Is a plan view corresponding that of FIG. 1, except that
the osteotomy guide is shown in a second angular position;
FIG. 3. Is a plan view of the embodiment of the osteotomy guide
depicted in FIGS. 1, 2;
FIG. 4. is a perspective view showing the drill jig depicted in
FIGS. 1 and 2, as it would be disposed over the proximal one-third
of a canine tibia to a cranial tibial cuneiform osteotomy;
FIG. 5. is a perspective view corresponding to that of FIG. 4,
showing the osteotomy guide of FIGS. 1-3, disposed in a first
angular position over the drill jig, in which position a first bone
cut would be taken;
FIG. 6. is a perspective view corresponding to those of FIGS. 4 and
5, showing the osteotomy guide in a second angular position, in
which a second bone cut would be taken;
FIG. 7. is a schematic side elevation view of the canine tibia and
tibial-femur joint, showing the bone wedge being removed therefrom;
and
FIG. 8. is a schematic side elevation view corresponding that the
of FIG. 7, except that the tibia is shown rejoined with an
osteopathic compression plate mounted to hold the bone in position
for rejoinder.
DETAILED DESCRIPTION OF THE INVENTION
Construction of the Depicted Embodiment
The objects of the present invention are particularly well-achieved
when the invention takes the form of the apparatus depicted in the
figures The apparatus includes a drill jig 10, and an osteotomy
guide 12, the construction of these members being shown best in
FIGS. 1-3. Making reference to FIGS. 1 and 2, it can been seen that
the major planar surface of drill jig 10 is rectangular in
configuration, and includes a wedge-shaped recess 14 defined along
one of its major edges. Recess 14 extends across a major portion of
the width of drill jig 10 and terminates in a drill aperture 15,
the purpose of which will be described below. As shown in FIG. 1,
recess 14 subtends an angle alpha (a) for purposes which will
become evident as this description continues.
Drill jig 10 also includes a plurality of drilled holes or bores,
such bores being identified with numerals 16, 18, 20, 22, and 24.
Holes 16 and 18 are disposed on the so-called proximal side of
recess 14, while bores 20, 22, 24 are disposed on the so-called
distal side. Bores 16 and 18 extend at an angle with respect to the
lateral edges of drill jig 10 along an imaginary line which has
been indicated at 26 in FIG. 1. Bores 20, 22, 24, are preferably
aligned parallel to the major or lateral edges of drill jig 10
along an imaginary line 28. As shown in FIG. 1, lines 26 and 28
also intersect at the alpha (a) angle.
Bores 16, 18, 20, 22, and 24 are typically approximately 0.08
inches in diameter, although this size may be varied depending upon
the particular application. Drill jig 10 itself is normally three
inches in length, one inch wide and approximately 0.3 inches thick
if the jig is being used for cranial tibial cuneiform osteotomy on
a dog, but the size may vary depending upon the particular
application. Of course, if the apparatus is being used to perform
some other type of cuneiform osteotomy, its size vary substantially
from that suggested. Angle alpha (a) is normally approximately
22.5.degree., as this angle has been found to be suitable for most
cranial cuneiform osteotomies performed on dogs. Of course, if the
operation is being used for any other purpose, the angle might be
substantially different.
Osteotomy guide 12 is shown best in FIG. 3. It also is preferably
rectangular in configuration, and includes a pair of holes or bores
30, 32, and an angular slot 34 extending outwardly across a
substantial portion of its width, to one of its major or lateral
edges. The spacing between guide bores 30 and 32 is normally
identical to that of bores 16, 18, 20, 22, and 24, that is,
approximately 0.08 inches. Guide bores 30 and 32 are shown to be
aligned along an imaginary line 36 which is parallel to the major
or lateral edges of osteotomy guide 12.
Slot 34 extends at an angle of one-half alpha (a/2) with respect to
an imaginary line 38 which is showed to be perpendicular to both
lines 36 and the major or lateral edges of osteotomy guide 12. Like
recess 14, slot 34 terminates in an aperture 40 which is similar in
side and corresponds in location to aperture 15 of drill jig
10.
Use Of The Depicted Embodiment
While the use of drill jig 10 and osteotomy guide 12 will be
described in the context of a crucial tibial cuneiform osteotomy on
a dog, it should be appreciated that the apparatus may be used in a
wide variety of other cuneiform osteotomies. To facilitate this
description, FIGS. 4-8 depict in a schematic and simplified manner,
tibia 40, femur 42 and patella 44 of a dog.
Reference should be made to FIG. 7, to understand the purpose of
the cranial tibial cuneiform osteotomy. Line 46 indicates the
tibial plane upon which femur 42 rests. Because the tibial plane is
inclined with respect to the horizontal, an anterior or cranial
force, i.e., to the left as indicated in FIGS. 4-8, is exerted on
tibia 40. This so-called cranial tibial thrust is opposed by the
cranial cruciate ligament and contributes to the ligament's rupture
and prevents or dramatically slows its healing. Therefore, the
purpose of the cranial tibial cuneiform osteotomy is to realign the
tibia so that forces exerted by femur 42 are absorbed in
compression by tibia 40. By realigning the distal portion 48 of
tibia 40 by an angle equal to alpha, this object may be achieved.
Such realignment is shown in phantom FIG. 7.
FIG. 4 depicts jig 10 being positioned on and mounted to the
proximal one-third of tibia 40. More precisely, drill jig 10 is
positioned on the medial side of tibia 40 in the sagittal plane so
that the bone wedge to be removed is just distal to the tibial
crest. A pair of drill bits 50 and 52, are drilled into tibia 40
through jig bores 16 and 22, and are left in place. Drill bits 50
and 52 are sufficiently long that both drill jig 10 and osteotomy
guide 12 may be aligned using the drill bits; that is, the portion
of the drill bits extending outwardly from tibia 40 should be
substantially greater than the thickness of drill jig 10 and
preferably is longer than the combined thickness of drill jig 10
and osteotomy guide 12. Other holes are then drilled in tibia 40
through bores 18, 20, and 24 using a similar drill bit (not shown)
but that drill bit is removed.
Osteotomy guide 12 is then placed over drill jig 10 so that drill
bits 50 and 52 pass through guide bores 30 and 32, as shown in FIG.
5. This places angular slot 34 of osteotomy guide 12 in a first
angular position so that the surgeon may make his first cut in
tibia 40 using an osteometric saw (not shown). The walls 34a and
34b of angular slot 34 and walls 14a and 14b of recess 14 provide a
guide for the surgeon during this cutting operation. The relative
width of tibia 40 and the length of slot 34 will normally cause
entire severance of the tibia, although it is common that the
maniscus of the bone and the ligaments and muscles will hold the
tibia in place.
Once this first cut has been effected, osteotomy guide 12 is lifted
off drill bits 50 and 52 and is turned over end over end and
replaced over the drill bits 10 with slot 34 taking a second
angular position as shown in FIG. 6. A second cut is then taken,
again using walls 34a, 34b of slot 34 and walls 14a and 14b of
recess 14 as a guide. The presence of apertures 35 and 15 in
osteotomy guide 12 and drill jig 10, respectively, will normally
cause clean removal of a bone wedge, shown schematically at 54. As
noted above, however, it is possible that the maniscus, ligaments
and muscles will still hold the tibia together. These can be
severed using conventional surgical techniques. Without apertures
35 and 15, it is possible that a certain amount of bone would
remain adjacent the intersection of the two cuts, and would cause
problems in removing bone wedge 54.
Once the two cuts have been effected, guide 12, jig 10 and drill
bits 50 and 52 are removed. Bone wedge 54 may then be pulled away
and the distal portion 48 of tibia 40 is shifted to the position
indicated in phantom in FIG. 7. Holes 56, 58, 60, 62, and 64, which
previously had been drilled through jig bores 16, 18, 20, 22, and
24, are then tapped, and an osteometric compression plate 66 is
mounted onto the tibia. Plate 66 is screwed into place through
holes 56, 58, 60, 62, and 64. To prevent infection, the area is
then typically irrigated with a neomycin, bacitracin, and polymixin
antibiotic solution.
With the distal one-third 48 of tibia 40 in its new position
depicted in FIG. 8, it can be seen that the tibial plane line 46 is
generally perpendicular to the longitudinal axis of the distal
one-third of the tibia. This prevents or at least minimizes the
cranial tibial thrust described above and permits unstressed
healing of the cranial cruciate ligament.
Having neutralized cranial tibial thrust, it is common to perform
supplemental techniques to accommodate for the reconfiguration of
the tibia. The technique most commonly used is the lateral
advancement of the biceps femoris muscle and the medial advancement
of the gracilis and semitendinosus. It should be understood,
however, that these last-mentioned procedures are optional and may
be dispensed with in some cases.
Other changes and modifications to the preferred embodiment
described herein will be apparent to those skilled in the art. Such
changes and modifications can be made without departing from the
spirit and scope of the present invention and without diminishing
its attendant advantages. It is therefore intended that such
changes and modifications be covered by the following claims.
* * * * *